5G Mobile Networks: Requirements, Enabling Technologies, and Research Activities 45
capital expense or CAPEX, and the cost for operation and management, which refers to
operational expense or OPEX, to be as low as possible. NFV [6] is the foundation for these
capabilities and is identified as the cornerstone of 5G core network solutions. Figure 2.9(b)
shows the reference architectural framework of NFV. Essentially, NFV refers to the relocation of network functions, which are traditionally implemented on dedicated costly
hardware platforms to software appliances running in the cloud environment or on general‐
purpose commodity servers. By operating the network function as software, it is easier for
mobile operators to dynamically scale the resources (computing, storage, and networking)
according to changes in traffic demands, and to faster time‐to‐market of new services.
In addition, the combination of SDN and NFV has encouraged the development of new
networking paradigms, such as network service chaining, and network slicing.
Figure 2.9 (a) SDN architecture, adapted from [5]; and (b) NFV architecture adapted from [6].
Network Device
Network Device
Network Device
Network Device
Network Device
Infrastructure Layer
Control Layer
Application Layer
SDN
Control
Software
Network Service
Network Service
Network Service
Network Service
Network Service
Business Applications
API
API
API
Southbound Interface
(e.g., OpenFlow)
(a)
Compute
Storage
Network
Hardware Resources
Virtualization Layer
Virtual
Compute
Virtual
Storage
Virtual
Network
NFV Infrastructure (NFVI)
VNF
VNF
VNF
VNF
Virtualized Network Functions (VNFs)
NFV Management & Orchestration (MANO)
(b)